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  • The most basic function of bodily fat is self-storage of food reserves.

  • In prehistoric times, natural selection favored genotypes that could endure harsh conditions by stocking the most fat.

  • With chronic malnutrition being the norm for most of human history, genetics evolved to favor fat storage.

  • So when did body fat become problematic?

  • The negative impacts of being overweight were not even noted in medical literature until as late as the 18th century.

  • Then, technological advances coupled with public health measures resulted in the betterment of the quantity, quality, and variety of food.

  • Sustained abundance of good food enabled a healthier population to boom economically.

  • Output increased, and with it, leisure time and waistlines.

  • By the mid 19th century, being excessively overweight, or obese, was recognized as a cause of ill health, and another century later, declared deadly.

  • What is the distinction between being overweight and being obese?

  • A calculation called the BMI breaks it down for us.

  • For example, if someone weighs 65 kilgorams and is 1.5 meters tall, they have a BMI of about 29.

  • Obesity is a condition of excess body fat that occurs when a person's BMI is above 30, just over the overweight range of 25 to 29.9.

  • While BMI can be a helpful estimate of healthy weight, actual body fat percentage can only really be determined by also considering information like waist circumference and muscle mass.

  • Athletes, for instance, have a naturally higher BMI.

  • So how does a person become obese?

  • At its most basic, obesity is caused by energy imbalance.

  • If the energy input from calories is greater than the energy output from physical activity, the body stores the extra calories as fat.

  • In most cases, this imbalance comes from a combination of circumstances and choices.

  • Adults should be getting at least 2.5 hours of exercise each week, and children a whole hour per day.

  • But globally, one in four adults and eight out of ten adolescents aren't active enough.

  • Calorie-dense processed foods and growing portion sizes coupled with pervasive marketing lead to passive overeating.

  • And scarce resources, and a lack of access to healthy, affordable foods creates an even greater risk in disadvantaged communities.

  • Yet, our genetic makeup also plays a part.

  • Studies on families and on separated twins have shown a clear causal hereditary relationship to weight gain.

  • Recent studies have also found a link between obesity and variations in the bacteria species that live in our digestive systems.

  • No matter the cause, obesity is an escalating global epidemic.

  • It substantially raises the probability of diseases, like diabetes, heart disease, stroke, high blood pressure, and cancer.

  • It affects virtually all ages, genders, and socioeconomic groups in both developed and developing countries.

  • With a 60% rise in child obesity globally over just two decades, the problem is too significant to ignore.

  • Once a person is obese, the climb to recovery becomes progressively steeper.

  • Hormonal and metabolic changes reduce the body's response to overeating.

  • After losing weight, a formerly overweight person burns less calories doing the same exercises as a person who is naturally the same weight, making it much more difficult to shed the excess fat.

  • And as people gain weight, damaged to signaling pathways makes it increasingly difficult for the brain to measure food intake and fat storage.

  • There is, however, some evidence that well-monitored, long-term changes in behavior can lead to improvements in obesity-related health issues.

  • And weight loss from sustained lifestyle changes, or invasive treatments like bariatric surgery, can improve insulin resistance and decrease inflammation.

  • What was once an advantage for survival is now working against us.

  • As the world's population continues to slow down and get bigger, moving and consciously eating our way towards a healthier weight is essential to our overall well-being.

  • And with the epidemic affecting every country in the world for different socioeconomic reasons, obesity cannot be seen as an isolated issue.

  • More global measures for prevention are essential to manage the weight of the world.

The most basic function of bodily fat is self-storage of food reserves.

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